| China has an18000km long coast line and abundant seaweeds resources. Inaddition, China is the dominant nation in world seaweeds culture, and also at the headof basic theory study. In order to get the further development in this field, much moreresources should be researched, including the resources that we do not understand orwe have understood but need further study. However, identifications of seaweeds aresometimes difficult due to their simple and convergent appearance. Morphologicalcharacters of seaweeds are often changeable under various conditions. In some cases,the differences between the species are rare, unknown life cycles also pose moredifficulties in species identification. Even the experts may face problems if theiridentification is solely depending on morphological characteristics. Such asGracilariopsis lemaneiformis, some researchers believe that it belongs to theGracilaria; but other experts proper that the Gracilariopsis lemaneiformis shouldtransfer to other genus, depending on different morphological characteristics. Anoften encountered problem in investigating benthic diatoms is also the accuratebiological identification.The goal of this research is to study the algae DNA Barcodes for helping solve theidentification difficulties. It included:(1) three DNA Markers, COI (cytochromeoxidase subunit I), UPA (universal plastid amplicon, domain V of23S rRNA), andITS (nuclear internal transcribed spacer) were employed to analyze common speciesof intertidal red seaweeds in Qingdao for selecting proper DNA sequence as standardRhodophyta DNA Barcode. The selected Markers were utilized to research thesubtidal red seaweeds resource in Qingdao;(2) sequences of three molecular markers (18S rRNA, cox2-3intergenic spacer and RUBISCO spacer), in combination withdata from GenBank, were used to analyze the phylogentic relations of Gracilariaspecies collected from the coast of China;(3) the SSU (18S rRNA) and rbcL is usedinitially to help identify the isolated benthic diatoms. The results showed that:(1): COI and UPA sequences could identify samples to species level. Among them,COI was a sensitive marker. However, not all the tested species gave PCRamplification products due to lack of the universal primers. The second barcode UPAhad effective universal primers but needed to be tested for the effectiveness ofresolving closely related species. For the further identification, the two sequencesshould be combined used. More than one ITS sequence types were found in somespecies in this investigation, which might lead to confusion in further analysis.Therefore ITS sequence is not recommended as a universal barcode for red seaweedsidentification. In subtidal red seaweeds resources research, two species Schizymeniadubyi and Polyopes lancifolius which not recorded in Qingdao were found. Some wildalgal turf, such as Pyropia yezoensis was also found in this study, they were veryimportant in further study.(2): In phylogenetic analysis of Gracilaria, phylogenetic trees based on cox2-3andRUBISCO spacer sequences exhibited the same pattern but differed slightly from thatof the18S rRNA-based phylogenetic tree due to a higher degree of conservation ofthe latter. Gracilaria textorii was sister to G. chouae in all three trees, showing theclose relationship between the two species. The results further confirmed that theGracilariopsis lemaneiformis did not belong to the genus Gracilaria. Results alsoindicate an earlier evolution status of Gracilariopsis lemaneiformis based on thesethree sequence comparisons.(3): SSU sequence was recommended to be used initially in most cases todiscriminate samples to genus or family level. Based on scanning electronicmicroscopy (SEM) and sequence comparisons of two genes (SSU, rbcL), the sampleswere identified to be Navicula perminuta, N. pseudacceptata, N. vara and N.rhynchocephala, respectively. |
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